1. Chapter 20 Drugs Used to Treat Dysrhythmias

2. the heart pumps blood to itself through coronary arteries
the heart pumps blood to itself through coronary arteries and to the rest of the body’s tissues
there are 2 phases of heart action:
diastole: resting phase, heart chambers fill with blood, heart is relaxed in this phase
systole: working phase, heart contracts, blood is pumped through the vessels when the heart contracts
systole and diastole make up the cardiac cycle
the conduction system (electrical system) controls the cardiac cycle
heart muscle must relax and fill with blood and contract to pump blood, in a coordinated fashion. Otherwise cells do not get enough blood and oxygen

3. to coordinate the cardiac cycle the heart’s muscle fibers are linked together
an electrical impulse starts in wall of right atrium, it’s conducted to muscles fibers in right and left atria, causing the atria to contract. Then the impulse moves to the ventricles, and causes them to contract
for every heartbeat an electrical impulse is conducted through the heart

4. 4 structures in the heart wall make up the conduction system (see fig
4 structures in the heart wall make up the conduction system (see fig pg. 256):
sino-atrial node (SA node)
atrio-ventricular node (AV node)
atrio-ventricular bundle (AV bundle aka bundle of His)
purkinje fibers

5. SA node: starts the impulse in the right atrium, its also called the
SA node: starts the impulse in the right atrium, its also called the pace-maker. It sets the beat of the heart
the electrical impulse travels from the SA node to the right and left atria
the right and left atria contract as the impulse travels through them. Blood pumps to ventricles
electrical impulse reaches AV node, it is at the bottom of the right atrium near the right ventricle
the impulse travels through the AV node to the AV bundle, aka bundle of His, in the wall separating the right and left ventricles
AV bundle has right and left branches, they extend to all parts of the ventricular wall
the right bundle branch conducts the impulse to the right ventricle
left bundle branch conducts the impulse to the left ventricle
Purkinje fibers branch into the myocardium from the right and left bundle branches
when impulse reaches the ventricular muscle, the ventricles contract
after contracting the ventricles relax

6. arrhythmia: without rhythm
dysrhythmia: an abnormal rhythm
there is a disturbance in the normal electrical conduction causing:
an abnormal heart muscle contraction
an abnormal heart rate
areas outside the SA node can act as a pacemaker, this causes an irregular heart beat
some rhythms are life-threatening
blocks can occur in the conduction system, block prevents impulse from traveling in a normal manner, can be life- threatening

7. electrocardiograms (ECGs): record the electrical activity
electrocardiograms (ECGs): record the electrical activity of the conduction system
this is recorded in waves
waves give the cardiac cycle a distinct appearance
each wave represents electrical activity in a certain part of the heart
the P wave, QRS complex, and T wave are the major parts of cardiac cycle
if a problem occurs in a part of the conduction system, the wave for that part appears abnormal
by studying ECG doctor determines the site of problem in the conduction system or the area of heart muscle damage
see fig pg. 257

8. Types of Dysrhythmias:
normal sinus rhythm impulses start in SA node
the heart rate is between beats per minute
various heart disease cause changes in conduction system
dysrhythmias are classified by origins within the heart tissues
Supraventricular dysthythmias: these develop above the bundle of His:
Sinus tachycardia: heart rate is rapid, Impulses start in SA node
(fig 20-4 p. 258)
Sinus bradycardia: heart rate is slow, impulses start in SA node
(fig 20-5)
Premature atrial contraction (PAC): SA node sends out impulse early (fig 20-6)
Paroxysmal atrial tachycardia (PAT): normal rhythm that suddenly turns into tachycardia. Bursts(paroxysms) of tachycardia occur. The tachycardia stops suddenly. (fig 20-7)

9. atrial flutter: impulses start in the atria at a rapid rate
supraventricular dysrhythmias cont…
atrial flutter: impulses start in the atria at a rapid rate
-ventricles do NOT respond to every impulse (fig 20-8),
-more P waves than QRS complexes
-QRS complexes occur at regular impulses
-persons pulse is regular
atrial fibrillation: impulses start in atria at multiple sites
-no P waves
-Impulses are conducted to the ventricles at irregular intervals (fig 20-9)
-pulse is irregular.
-Atria quiver, not contract
-Blood not pumped from atria to ventricles in normal amounts, thus inadequate blood pumped to rest of body
junctional rhythms: impulses start in the AV node, there are no P waves (fig ), these can occur at normal or slow rates

10. blocks in conduction pathways: -described by degree of the block:
first-degree heart block:
-impulse takes longer to travel from SA node to AV note
-PR interval is longer than normal (fig 20-11)
-rhythm is regular
second-degree heart block:
-some impulses from SA node do not reach ventricles
-Impulses from SA node take longer and longer to travel through the AV node until a beat is skipped
-QRS complex does NOT follow a P wave (fig 20-12)
-rhythm is irregular
third-degree heart block:
-impulse is blocked between the atria and ventricles (fig 20-13)
-Impulse cannot reach the ventricles
-ventricles must create their own impulses
-P waves appear but are not related to QRS complexes
-QRS complexes are wider than normal
-Heart rate is very slow
-LIFE THREATENING DYSRHYTHMIA!!!

11. Ventricular dysrhythmias: these develop below the bundle of His:
Premature ventricular contraction (PVC):
-impulse created in ventricles
-occurs earlier than the next regular beat
-QRS complex is wide and bizarre (fig 20-14)
-unifocal PVCs come from one site, all look the same
-multifocal PVCs created in many sites (fig )
-bigeminy: every second complex is a PVC (fig 20-16)
-trigeminy: every third complex is a PVC
-two PVCs can occur in a row (fig 20-17)
-they can be unifocal or multifocal, called coupled PVCs
-a run of ventricular tachycardia is several PVCs in a row (fig ) rhythm returns to normal
-PVCs can mean heart muscle is irritable
-LIFE THREATENING!!!

12. Ventricular dysrhythmias cont…. Ventricular tachycardia (VT):
-impulses start in ventricles
-heart rate can change from beats per minute
-QRS complexes are wide and bizarre
-rhythm looks like a series of PVCs (fig 20-19)
-LIFE THREATENING!!!
-if not corrected it progresses to ventricular fibrillation
Ventricular fibrillation (VF or V fib):
-impulses start from multiple sites in ventricles
-P waves and QRS complexes are not present (fig 20-20)
-ventricles quiver, not contract
-DEADLY!!! person is in cardiac arrest
Asystole:
-means no contraction
-no electrical action occurs in heart (fig 20-21)
-DEADLY!!! person in cardiac arrest

13. conduction system tissues are affected by calcium and sodium
ion is atom with electrical charge
atom is smallest part of an element
element is a simple substance that cannot be broken down into another substance
calcium and sodium are elements:
-calcium: SA and AV nodes depend on calcium ions for electrical conduction
-sodium: atrial muscle, His-Purkinje system, and ventricular muscle depend on sodium for contraction

14. Drug Therapy for Dysrhythmias:
Anti-dysrhythmic agents are drugs used to prevent or correct abnormal heart rhythms
depending on drug, anti-dysrhythmic agents affect the heart’s conduction system by:
-inhibiting sodium ion movement, this depresses the heart muscle
-prolonging or shortening the duration of electrical stimulation on the cells
-increasing or decreasing the time between electrical impulses
-slowing the conduction rate between the atria and ventricles

15. Delegation Guidelines Drug Therapy for Dysrhythmias:
Some drugs used to treat dysrhythmias are given parenterally- by intramuscular or intravenous injection. Because you do NOT give parenteral dose forms, they are not included in this chapter. Should a nurse delegate the administration of such to you, you must:
- remember that parenteral dosages are often very different from dosages other routes
-Refuse the delegation. Make sure to explain why. Do NOT just ignore the request. Make sure the nurse knows that you cannot give drug and why

16. Drug therapy for Dysrhythmias
amiodarone hydrochloride (Cordarone):
-slows the rate of electrical conduction, increases the time between contractions
-drug is given to convert the following dysrhythmias to normal sinus rhythm:
- supraventricular tachycardias – rapid arrhythmias
that occur above the bundle of His
- atrial fibrillation
- atrial flutter
- bradycardia-tachycardia syndromes
- ventricular tachycardia
- ventricular fibrillation

17. Assisting With the Nursing Process
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
amiodarone hydrochloride (Cordarone):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (for 1 min), and respirations
PLANNING: oral dose forms are: 100, 200, 400mg tablets
IMPLEMENTATION: initial adult dose is mg daily in divided doses for 1-3 weeks. Then a dosage of mg is given for about 1 month, lowest effective dose should be used (usually 400mg) EVALUATION: report and record:
-fatigue, tremors, involuntary muscle movements, sleep problems, numbness and tingling, coordination problems, dizziness, confusion. Many of these resolve when dose is reduced or drug is discontinued, provide for safety
-dyspnea on exertion, non-productive cough, chest pain with breathing: symptoms resolve when drug is discontinued
blurred vision, narrowed peripheral vision, halos: provide for safety, resolve when drug is discontinued
nausea, vomiting, constipation, abdominal pain, anorexia: common with high dosages, resolve with lower dosages or divided doses
dysrhythmias: drug may cause dysrhythmias or cause existing ones to worsen
skin reactions: rash, burning, tingling, redness, blistering: from exposure to sun (photo- sensitivity). person should wear sunscreen, long sleeved shirts, avoid exposure to sun
anorexia, nausea, vomiting, jaundice: may signal liver toxicity

18. -Beta blockers are widely used as anti-dysrhythmic agents (ch.14)
Drug therapy for Dysrhythmias cont…
-Beta blockers are widely used as anti-dysrhythmic agents (ch.14)
-by blocking beta receptors, they block the heart’s response to sympathetic nerve stimulation
-heart rate, BP and cardiac output are reduced
-see table 14-2 for beta blockers used to treat dysrhythmias
-they are effective in converting the following dysrhythmias to normal sinus rhythm:
various ventricular dysrhythmias
sinus tachycardia
paroxysmal supraventricular tachycardia
premature ventricular contractions
atrial flutter when tachycardia is present
atrial fibrillation when tachycardia is present

19. Assisting With the Nursing Process
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
for beta blockers:
See chapter 14

20. Disopyramide (Norpace):
Drug Therapy for Dysrhythmias cont…
Disopyramide (Norpace):
Prolongs the simulation on the cells and increases the time between electrical impulses
Effective in converting the following dysrhythmias to normal sinus rhythm:
atrial fibrillation
paroxysmal supraventricular tachycardia
runs of ventricular tachycardia
ventricular tachycardia

21. Assisting With the Nursing Process disopyramide (Norpace):
Drug therapy for Dysrhythmias
Assisting With the Nursing Process
disopyramide (Norpace):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations, ask about bowel elimination and urination
PLANNING: oral dose form: 100, 150mg tablets
100, 150mg extended release capsules
IMPLEMENTATION: dosage depends on person needs, usually mg/day, usually 150mg every 6 hours EVALUATION: report and record:
- dry mouth, nose and throat: provide oral hygiene, give, hard candy or ice chips if care plan allows
bradycardia, signs of heart failure(ch. 21): signs of myocardial toxicity
difficulty starting a urine stream: run tap water or immerse hand in water, measure input/output
constipation, abdominal distention, flatus: ask about bowel elimination and expelling gas

22. flecainide acetate (Tambocor):
Drug therapy for Dysrhythmias cont…
flecainide acetate (Tambocor):
slows conduction rate through atria and ventricles
effective in converting the following dysrhythmias to normal sinus rhythm:
ventricular tachycardia
paroxysmal supraventricular tachycardia
premature ventricular contractions

23. Assisting With the Nursing Process flecainide acetate (tambocor):
Drug therapy for Dysrhythmias
Assisting With the Nursing Process
flecainide acetate (tambocor):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations, observe for signs and symptoms of heart failure (ch.21)
PLANNING: oral dose forms: 50, 100, 150 mg tablets
IMPLEMENTATION: initial dose is 100mg every 12 hours, increased by 50mg twice a day every 4 days. Usual dose is 150mg 2x/day,
max daily dose is 400mg EVALUATION: report and record:
dizziness, headache, constipation, nausea: mild, tend to resolve
vision disturbances: provide for safety
signs and symptoms of heart failure (ch 21), may cause heart failure or existing heart failure to worsen
dysrhythmias: may cause or worsen dysrhytmias

24. mexiletine (Mexitil):
Drug therapy for Dysrhythmias cont…
mexiletine (Mexitil):
shortens the duration of electrical stimulation on the cells
increases the time between electrical impulses
effective in converting the following dysrhythmias to normal sinus rhythm:
ventricular tachycardia
premature ventricular contractions

25. Assisting With the Nursing Process mexiletine (Mexitil):
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
mexiletine (Mexitil):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations, ask about GI symptoms, observe orientation to person, time and place. Observe for agitation
PLANNING: oral dose forms: 150, 200, 250mg tablets
IMPLEMENTATION: usual dose is mg every 8 hours, give drug with food or antacids, if ordered EVALUATION: report and record:
nausea, vomiting, indigestion: occur usually with higher doses
dysrhythmias: may cause them or worsen existing ones
fine hand tremors, coordination problems, light-headedness, blurred vision, double vision, involuntary eye movement, difficult speech, confusion, numbness and tingling, drowsiness, seizures: signal toxic effect on CNS
confusion: observe for confusion and persons orientation to person, time and place, provide for safety

26. moricizine (Ethmozine):
Drug therapy for Dysrhythmias cont…
moricizine (Ethmozine):
slows the conduction rate between atria and ventricles
effective in converting ventricular dysrhythmias to normal sinus rhythm
it can cause other dysrhythmias, it is used when benefits are greater than the risk

27. Assisting With the Nursing Process moricizine (Ethmozine):
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
moricizine (Ethmozine):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations, ask about GI symptoms, observe orientation to person, time and place. Observe for agitation and confusion
PLANNING: oral dose forms: 200, 250, 300mg tablets
IMPLEMENTATION: initial dose is 200mg every 8 hours, may be increased by 150mg every 3 days. usual dosage is between mg/day, given in divided doses around the clock, give drug with food and milk EVALUATION: report and record:
hypotension, dizziness: may occur with starting drug, usually subside, provide for safety
nausea: give drug with food or milk
dysrhythmias: may cause them or worsen existing
euphoria, confusion: observe orientation to person time and place, provide for safety

28. procainamide hydrochloride (Procanbid):
Drug therapy for Dysrhythmias cont…
procainamide hydrochloride (Procanbid):
prolongs the duration of electrical stimulation on the cells
increases the time between electrical impulses
effective in converting the following dysrhythmias to normal sinus rhythm:
ventricular dysrhythmias
supraventricular dysrhythmias
atrial flutter
atrial fibrillation

29. Assisting With the Nursing Process
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
procainamide hydrochloride (Procanbid):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations
PLANNING: oral dose forms: 250, 375, 500mg capsules/tablet
and 250, 500, 750, 1000mg sustained-release tablets
IMPLEMENTATION: initial dose is g, followed with 750mg one hour later if arrhythmia is still present, dosage is maintained at g every 4-6 hours (some every 3-4), given in divided doses around the clock, give with food or milk
EVALUATION: report and record:
-drowsiness, sedation, dizziness, hypotension: provide for safety
- fever, chills, joint and muscle pain, skin eruptions: may signal changes in white blood cells

30. propafenone (Rythmol):
Drug therapy for Dysrhythmias cont…
propafenone (Rythmol):
slows the conduction rate between the atria and ventricles
effective in converting atrial fibrillation and ventricular dysrhythmias to normal sinus rhythm
it can cause other dysrhythmias so it is used when benefits are greater than risks

31. Assisting With the Nursing Process propafenone (Rhythmol):
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
propafenone (Rhythmol):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations, ask about GI symptoms
PLANNING: oral dose forms: 150, 225, 300mg tablets
and 225, 325 and 425 extended-release tablets
IMPLEMENTATION: initial dose is 150mg every 8 hours, every 3-4 days dosage may be increased to 225mg every 8 hours, then 300mg every 8 hours (900mg daily), drug is given around the clock, ask nurse what to do if a dose is missed
EVALUATION: report and record:
- dizziness: provide for safety
- nausea, vomiting, constipation: give drug with food or milk
- dysrhythmias: drug may cause them or worsen existing

32. shortens the duration of electrical stimulation on the cells
Drug therapy for Dysrhythmias cont…
quinidine:
shortens the duration of electrical stimulation on the cells
increases the time between electrical impulses
slows the heart rate and changes a rapid, irregular pulse to a slow, regular pulse
it is effective in converting the following dysrhythmias to normal sinus rhythm:
atrial flutter
atrial fibrillation
paroxysmal supraventricular tachycardia
premature ventricular contractions

33. Assisting With the Nursing Process
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
quinidine:
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations (person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (1 min) and respirations, ask about bowel elimination
PLANNING: oral dose forms for quinidine sulfate: 200, 300mg tablets and 300mg sustained-release tablets
quinidine gluconate: 324mg sustained-release tablets
IMPLEMENTATION: quinidine sulfate: mg orally 3-5x/day, max single dose is mg, give with food/milk
quinidine gluconate: mg every 8-12 hours
EVALUATION: report and record:
diarrhea: common with start of drug, usually subsides
dizziness, faintness: usually subside, provide for safety
hearing loss, headache, tinnitus, increasing mental confusion, rash, chills, fever: result from excess quinidine
hypotension: may occur if person is also on diuretics or anti-hypertensive meds, provide for safety